You lose no functionality, and you gain the benefit of consistency (and possibly intuitiveness, depending on your intuition).

Consistency isn't exactly a hallmark of Perl. (Take context as an example. Or the wide variety of behavior you get from builtins. Or the whole philosophy of TMTOWTDI.) The tradeoff it often makes is consistency for flexibility. Perl's flexibility makes it great! But, it pushes the burden of consistency off to us, the developers.

And, it's partially in the interest of consistency that I would reject the advice to use /msx all the time because I expect that the great volume of Perl code written so far does not follow that advice. I'm also fairly certain that I'm not the only one who has seen [^\n] in someone's regex and suggested that using a lone dot would be more Perlish.

The more practical reason, however, is that when I see /m or /s or \A or \Z these are strong visual cues that immediately indicate the data a given regex is dealing with probably has embedded newlines. I'd really rather not give that up.

-sauoq
"My two cents aren't worth a dime.";